NAME

    boolean - Boolean support for Perl

VERSION

    This document describes boolean version 0.46.

SYNOPSIS

        use boolean;
    
        do &always if true;
        do &never if false;
    
        do &maybe if boolean($value)->isTrue;

    and:

        use boolean ':all';
    
        $guess = int(rand(2)) % 2 ? true : false;
    
        do &something if isTrue($guess);
        do &something_else if isFalse($guess);

DESCRIPTION

    Most programming languages have a native Boolean data type. Perl does
    not.

    Perl has a simple and well known Truth System. The following scalar
    values are false:

        $false1 = undef;
        $false2 = 0;
        $false3 = 0.0;
        $false4 = '';
        $false5 = '0';

    Every other scalar value is true.

    This module provides basic Boolean support, by defining two special
    objects: true and false.

RATIONALE

    When sharing data between programming languages, it is important to
    support the same group of basic types. In Perlish programming
    languages, these types include: Hash, Array, String, Number, Null and
    Boolean. Perl lacks native Boolean support.

    Data interchange modules like YAML and JSON can now use boolean to
    encodedecoderoundtrip Boolean values.

FUNCTIONS

    This module defines the following functions:

    true

      This function returns a scalar value which will evaluate to true. The
      value is a singleton object, meaning there is only one "true" value
      in a Perl process at any time. You can check to see whether the value
      is the "true" object with the isTrue function described below.

    false

      This function returns a scalar value which will evaluate to false.
      The value is a singleton object, meaning there is only one "false"
      value in a Perl process at any time. You can check to see whether the
      value is the "false" object with the isFalse function described
      below.

    boolean($scalar)

      Casts the scalar value to a boolean value. If $scalar is true, it
      returns boolean::true, otherwise it returns boolean::false.

    isTrue($scalar)

      Returns boolean::true if the scalar passed to it is the boolean::true
      object. Returns boolean::false otherwise.

    isFalse($scalar)

      Returns boolean::true if the scalar passed to it is the
      boolean::false object. Returns boolean::false otherwise.

    isBoolean($scalar)

      Returns boolean::true if the scalar passed to it is the boolean::true
      or boolean::false object. Returns boolean::false otherwise.

METHODS

    Since true and false return objects, you can call methods on them.

    $boolean->isTrue

      Same as isTrue($boolean).

    $boolean->isFalse

      Same as isFalse($boolean).

USE OPTIONS

    By default this module exports the true, false and boolean functions.

    The module also defines these export tags:

    :all

      Exports true, false, boolean, isTrue, isFalse, isBoolean

DEPRECATIONS

    This module offered an export tag, -truth, that overrides the Perl
    interpreter's internal values for true and false. This has been found
    to corrupt the interpreter in some circumstances. Also, these overrides
    will no longer be possible as of Perl 5.22. Therefore, the -truth
    import tag is deprecated.

JSON SUPPORT

    JSON::MaybeXS (or less preferably JSON.pm ) will encode Perl data with
    boolean.pm values correctly if you use the convert_blessed option:

        use JSON::MaybeXS;
        use boolean -truth;
        my $json = JSON::MaybeXS->new->convert_blessed;
        say $json->encode({false => (0 == 1)});     # Says: '{"false":false}',

AUTHOR

    Ingy döt Net <ingy@cpan.org>

COPYRIGHT AND LICENSE

    Copyright 2007-2016. Ingy döt Net.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

    See http://www.perl.com/perl/misc/Artistic.html

